Pressure vessel and method for cooling a pressure vessel

Abstract

The present invention relates to an arrangement for treatment of articles by hot pressing and preferably by hot isostatic pressing. In particular, the present invention relates to such an arrangement capable of obtaining a rapid rate without the need of special purpose valves for the cooling. A furnace chamber is provided inside the pressure vessel of the arrangement and a heat insulated casing arranged to surround the furnace chamber. A bottom insulating portion is arranged beneath the furnace chamber. Further, a fan having a controllable number of revolutions for circulating the pressure medium within the furnace chamber is arranged in the pressure vessel, and preferable within the furnace chamber. At least one feeding passage is arranged to allow feeding of pressure medium from a region being colder than a region within the furnace chamber towards an inlet of the fan, wherein an amount of pressure medium being fed to the inlet of the fan can be controlled by adjusting operational parameters of the fan.

The invention claimed is: 
     
       1. A pressing arrangement for hot pressing, comprising:
 a pressure vessel including a furnace chamber adapted to hold articles, which furnace chamber is provided inside the pressure vessel; 
 a heat insulated casing arranged to surround said furnace chamber; 
 a bottom insulating portion arranged beneath said furnace chamber; 
 a fan having an adjustable number of revolutions, said fan being arranged to provide a flow of pressure medium into said furnace chamber and a circulation of said pressure medium within the furnace chamber when operated; and 
 at least one valveless feeding passage having an outlet located at a radial and vertical distance relative said fan, said at least one valveless feeding passage being arranged to provide a connection during at least a steady state and a cooling state between a region, inside said pressure vessel and beneath said bottom insulating portion, and an inlet of said fan so as to enable, by increasing the number of revolutions of said fan to generate a sufficient pressure difference between said region and a passage above said bottom insulating portion and below said furnace chamber, a flow of pressure medium from said region to said inlet for mixing said flow from said region with a flow of pressure medium in said passage, wherein said flow can be controlled by adjusting said number of revolutions of said fan, wherein said at least one valveless feeding passage is at least one conduit arranged in said bottom insulating portion at a radial distance from a central axis of said fan and wherein a respective outlet of said conduit is located in connection to a passage above said bottom insulating portion. 
 
     
     
       2. The pressing arrangement according to  claim 1 , wherein said fan is configured such that operation at a number of revolutions below a certain limit number of revolutions results in that said flow of pressure medium is impeded. 
     
     
       3. The pressing arrangement according to  claim 2 , wherein said fan is configured such that operation at a variable number of revolutions above said certain limit number of revolutions results in a variable flow of cold pressure medium through said at least one valveless feeding passage towards said inlet of said fan, wherein the amount of cold pressure medium fed into said furnace chamber can be varied. 
     
     
       4. The pressing arrangement according to  claim 3 , wherein said at least one valveless feeding passage is arranged with dimensions such that said fan and said at least one valveless feeding passage co-operate to achieve said substantially impeded flow of pressure medium and said variable flow of cold pressure medium, respectively. 
     
     
       5. The pressing arrangement according to  claim 3 , wherein said respective outlet of said at least one valveless feeding passage is located at a radial and vertical distance from an inlet of a guiding passage in said heat insulated casing such that said at least one valveless feeding passage and said inlet of said guiding passage co-operate to achieve said substantially impeded flow of pressure medium and said variable flow of cold pressure medium. 
     
     
       6. The pressing arrangement according to  claim 1 , wherein said at least one conduit is arranged to extend into said passage such that said respective outlet is located at a distance from said bottom insulation portion. 
     
     
       7. The pressing arrangement according to  claim 1 , wherein said at least one valveless feeding passage is arranged such that a respective outlet of said valveless feeding passage is located in connection to said central passage. 
     
     
       8. The pressing arrangement according to  claim 1 , wherein support means for supporting a load compartment within said furnace chamber is arranged such that pressure medium is allowed to flow into said passage above said bottom insulation portion. 
     
     
       9. The pressing arrangement according to  claim 8 , wherein said support means is provided with through holes arranged to allow pressure medium to flow into said passage above said bottom insulation portion. 
     
     
       10. A pressing arrangement for hot pressing, said pressing arrangement comprising:
 a pressure vessel including a furnace chamber adapted to hold articles, which furnace chamber is provided inside the pressure vessel; 
 a heat insulated casing arranged to surround said furnace chamber; 
 a bottom insulating portion arranged beneath said furnace chamber; 
 a fan having an adjustable number of revolutions, said fan being arranged to provide a flow of pressure medium into said furnace chamber and a circulation of said pressure medium within the furnace chamber when operated; and 
 at least one valveless feeding passage having an outlet located at a radial and vertical distance relative said fan, said at least one valveless feeding passage being arranged to provide a connection during at least a steady state and a cooling state between a region, inside said pressure vessel and beneath said bottom insulating portion, and an inlet of said fan, so as to enable, by increasing the number of revolutions of said fan to generate a sufficient pressure difference between said region and a passage above said bottom insulating portion and below said furnace chamber, a flow of pressure medium from said region to said inlet wherein adjusting said number of revolutions of said fan results in said flow being mixed with a flow of pressure medium in said at least one valveless feeding passage, wherein said at least one valveless feeding passage is at least one conduit arranged in said bottom insulating portion at a radial distance from a central axis of said fan and wherein a respective outlet of said conduit is located in connection to a passage above said bottom insulating portion.